1. Field of the Invention
The present invention relates generally to an auditory prosthesis and, more particularly, to an endosteal electrode carrier member for use with an auditory prosthesis to stimulate the cochlea.
2. Related Art
Hearing loss, which may be due to many different causes, is generally of two types, conductive and sensorineural. In some cases, a person may have hearing loss of both types. Conductive hearing loss occurs when the normal mechanical pathways for sound to reach the hair cells in the cochlea are impeded, for example, by damage to the ossicles. Conductive hearing loss is often addressed with conventional hearing aids, which amplify sound so that acoustic information can reach the cochlea.
In many people who are profoundly deaf, however, the reason for their deafness is sensorineural hearing loss. This type of hearing loss is due to the absence or destruction of the hair cells in the cochlea which transduce acoustic signals into nerve impulses. Those suffering from sensorineural hearing loss are thus unable to derive suitable benefit from conventional hearing aids due to the damage to or absence of the mechanism for naturally generating nerve impulses from sound.
It is for this purpose that another type of auditory prosthesis, a cochlear implant (also commonly referred to as cochlear prostheses, cochlear devices, cochlear implant devices, and the like; generally and collectively referred to has “cochlear implants” herein) has been developed. These types of auditory prostheses bypass the hair cells in the cochlea, directly delivering electrical stimulation to the auditory nerve fibers via an implanted electrode assembly. This enables the brain to perceive a hearing sensation resembling the natural hearing sensation normally delivered to the auditory nerve.
Despite the enormous benefits offered by cochlear implants, one potential disadvantage of placement of the electrode assembly within the scala tympani is that it is necessary to breach the internal canals of the cochlea, generally the scala tympani. Breaching the scala tympani may adversely affect the hydrodynamic behavior of the cochlea and/or damage existing hair cells thereby preventing or at least reducing the likelihood that any residual hearing of the recipient will be preserved. This may be problematic for those persons who would benefit from use of an implantable hearing device to improve hearing of relatively high frequencies but who have some residual hearing of relatively low frequencies. In such a case, the recipient is forced to trade off an existing residual capacity to hear relatively low frequency sounds against the desirability of being able to have a hearing sensation of relatively high frequency sounds offered by an implantable hearing device.